Light modulation apparatus and light modulator control method

摘要

A light modulation apparatus (10) including a Mach-Zehnder type light modulator (2), a driver (3) for modulator outputting a control signal according to an input electric signal, a light branching circuit (5) branching the output light signal, and a bias control circuit (9) applying a bias voltage to the light modulator (2) based on the branched light signal, the apparatus further comprises: a burst pause state detection circuit (4) detecting a pause state of a burst signal included in the input electric signal; a photoelectric transducer (6) converting an output light signal branched by the light branching circuit (5) into an electric signal; a sampling circuit (7) extracting the electric signal converted while the pause state is detected by the bunt pause state; and a bias voltage adjustment circuit (8) adjusting a bias voltage value of the bias voltage based on a voltage level of the extracted electric signal.